


All Grown Up

by AfflictedwithAlliteration



Series: Hard Candy [1]
Category: Undertale (Video Game)
Genre: Alternate Universe - Underswap, F/M, Reader-Insert, Sort Of, dub-con
Language: English
Status: Completed
Published: 2017-10-16
Updated: 2018-08-22
Packaged: 2019-01-18 07:08:25
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,850
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12383346
Author URL: https://archiveofourown.org/users/AfflictedwithAlliteration/pseuds/AfflictedwithAlliteration
Summary: Of course you know Sans is an adult...don't you?





	1. Secret Touch

Papyrus looks at you, with the same indescribable expression as always, chin in his hand, smoke steadily passing through his teeth. His gaze drops from you slowly to the bundle of blue in your lap where Sans is happily seated scribbling down his daily reports.

“You know he’s an adult right?”

You frown at him, fingers twitching in Sans armor when you feel him tense and you fight the urge to defensively pull him closer. You can’t see his face but you’re sure he’s giving his brother some sort of pout judging by the amused smiled sprawling across Paps face.

“Yes?” You’re not sure what he’s asking but his smirk widens.

“You sure about that?” His eye lights are bright and you think he’s about to start laughing at you. This time you do tighten your hands around the smaller skeleton, it’s not you’re fault your too big to fit in Sans lap so he sits in yours. Besides it was Sans. He could sit where he wanted.

“Yes!”

“BROTHER, STOP BOTHERING THE HUMAN!”

This time Paps does laugh then stands, hands going into his pockets and strolls towards the door, “If you say so.”  
You’re not sure who he’s replying to.

* * *

As soon as Sans pencil stops moving you lift your head, cringing as your neck tingles, that had been a terrible position to sit in. You drop your forehead onto Sans shoulder and rub your neck irritably.

“HUMAN!” Sans bounces in your lap jolting your head up as he turns himself to face you, legs swinging idly against your thighs as he switches position. The proximity of his face makes your eyes cross until you pull your head back a bit, hand still on your neck.

“Yeah?”

“HUMAN WOULD YOU—“ If he was going to say anything else he gets distracted by your hands, gaze moving from your face to your neck, “OH! ARE YOU INJURED HUMAN?”

“I just leaned back on the chair wrong, necks sore is all. What were—ow! Sans be careful! What are you—hmm…feels nice…” You trail off as his magic fingers buzz around you neck, featherlight touches against your spine. You drop your head back onto his shoulder, giving him more access with a groan.

“IS THAT BETTER HUMAN?”

“Mm, yes.” You hum as his touches get firmer and he pulls you to him so your both slouched against the table and he can reach all the way down your back. The happy buzz of his magic makes you brain drift right up until his fingers ghost up your sides under your shirt, your body jerking up into his, “That tickles!”

“Sorry human.” His voice is quiet but sounds much less sorry than it should be and you’d tell him that if hands weren’t pressing just right against your ribs, not tickling anymore but you can hear him counting softly under his breath and smile against his shoulder.

The smile fades as his hands climb higher, thumb ghosting just under your bra and pausing his count. For a moment your both tense then his hands are on your back again. Safe territory. You swallow, realizing now how close you are, Paps words ringing in your ears. Right. Time to get up.

“Thanks Sans!” You chirp is louder than intended, trying to signal he can stop now but it simply startles him into tightening his hold, fingers digging into your sides just shy of painful as his magic buzzes into something like a shock. “Ow! Damn it Sans!”

“SORRY!” The pleasant buzz comes back and he still hasn’t let you go, “I’LL HEAL IT.”

“You'd better.”

And he does. You can feel his magic probe deeper, cool and sinking into the tingling muscles until you relax against him again. Your eyes drift shut at the sensation, even as his hands curl into your sides, alternating between running up your sides and stopping just shy of being pleasurable—and what. Not okay thoughts. Seriously. It Sans.

Its not okay for you to—and that is definitely a hand on your thigh, you can’t help but regret you choice of skirt today. His magic buzzes all the way up your thigh and you sigh, maybe you don’t regret it that much. It continues up, and even if you wanted to you can’t stop the sudden rush of heat between your legs, feeling guilty and strangely dirty as his hand continues up. It only stops when its reached your hip bone, darting around back to wrap around your waist.

Stupid Papyrus. You blame him for this entirely, he put the idea in your head with his big mouth. Okay, maybe he didn’t put it there but he brought it back to the forefront of your mind where it blazed brighter with every sweep of the small skeletons hands. Definitely time to get up before you did something stupid like—  
His other hand slips under the edge of your bra with ease—this is why wireless were bad—fingers grazing just under your nipple. You shudder so hard the table scratches against the ground, yup done, massage over. But his arm prevents you from doing more than leaning back to catch his eye and his very, very bright eye lights. Oh boy.

“Did that hurt?” His voice is lower than normal when you shift your hips, uncomfortable with your own thoughts. Breath hitching when he repeats the motion, fingers creeping higher almost imperceptibly. You’re supposed to be moving now but instead you smile a bit shakily.

“N-nope.” You’re a dirty, dirty terrible person you think as you hips shift again. Sans cocks his head at you, face going strangely blank before his gaze drops to your chest and this time his fingers brush directly over your nipple, his other hand tracing along the back of your skirt. 

“I feel better now! We can get up!” You hiss out with a jerk, pulling back and trapping his hand and your back against the chair but the other is still tingling on your chest. You lick your lips, avoiding his gaze because what the hell had you just done and let him do and you were corrupting Paps baby brother and he was gonna kill you!

“I AM NOT STUPID EITHER.”

“What?” Your gaze snaps to his, confused and distracted as his hand trails back up, caressing your collar bone gently, up your neck and chin until his finger tips rest against your lips. The drag of magic against them makes your hands tighten on his hips—and when the hell had they gotten there?!

“THE MAGNIFICENT SANS IS NOT A CHILD AND I AM NOT STUPID.”

“…okay?” Your confused, what is he talking—oh! “Is this about what Paps said earlier?”

“YES.”

“You know I—“ He hand drifts under the band of your skirt, skimming the top of your ass with purpose. Your eyes flutter shut and you try to speak against his fingers, “Sans that—“

“I know what I’m doing.” He says finally, quiet again, sounding both proud and maybe a little nervous and it kills any other thoughts. Heat floods your cheeks but your surprised theres any left when all of it suddenly wants to rush much farther south.

He’d been doing it intentionally. You swallow, he’d known exactly what you were doing, squirming under him, he’d known you’d been secretly getting off on the touches. You’re not sure whats worse, that you’d used his perceived innocence or that he had. When his finger idly dips past your lips you really, really don’t care because now you’re both on the same page.

You lick the tip of his finger and Sans lets out a small sound of surprise, your hands tighten on his hips, pulling him closer—

“I’m home, bro.”

The shriek of shock that leaves you is inhuman, Sans growl even more so but you manage to shove the small skeleton off. Papyrus enters the kitchen at a run, magic flaring from his eye but it only greeted to the sight of Sans on the floor and you struggling to adjust your clothes. The glow of his magic fades leaving an expression of equal parts annoyance, confusion, and amusement until it settles into a customary smirk when Sans yells something unflattering about his timing. Papyrus ignores it in favor of blowing smoke in your face, "Told you he's an adult.”

“Fuck off.” You hiss and stomp from the room, leaving the two brothers to bicker in the kitchen but you're not really angry because what the hell had you been about to do?! With Sans! You close your eyes as you try to massage away an oncoming headache. Stupid Paps. Stupid Sans. Stupid short skeleton parading around like he's not an all grown up and--you flush. Shower. You're going to take a shower.


	2. Not an Accident

**Summary for the Chapter:**

> Sans has forgotten all about the incident...or has he?

You weren’t sure what you were expecting but you had thought something would change. Or maybe you were just hoping it would. But neither you or Sans had spoken about the…incident and the only thing reminding you it wasn’t a dream were Paps stupid jokes. It made you grateful it was just you and Sans, moving around the kitchen in-sync as he cooks the meat and you wait for directions.

“SEASONINGS!”

“Coming!”

The teamwork keeps him from adding sprinkles by mistake while still allowing him to cook and allows you to season the food without offending him by telling him his seasonings suck. With a hum you go for the taco seasoning, handing it to Sans before twirling away freezing only when you feel a boney hand pat your ass. You tense and glance at Sans but his intense eye lights are focused on the browning meat. 

“THANK YOU, HUMAN!”

An accident but you tingle all the same and make a note to tell him to watch his hands later on.

* * *

“HUMAN!”

“What now?” You huff out irritably from your position, regretting Sans up on his offer to get you in shape. He clearly had no idea how to take it slow and your muscles already burned from the early exercise but Sans had insisted you ‘wind down’ but you thought he was just trying to kill you.

“YOUR POSTURE IS ALL WRONG!” 

“Yeah, well…oh well.” You gasp out, straining to reach your toes and waiting for him to say you can release the position but instead you hear the clomp of his boots from behind you. Then his hands are gliding up your back, pushing you farther down—

“Sans, that—“ Your words cut off as his hips press up against you, his hand running up tp your shoulders before pushing you down farther until your finger tips brush the ground. His hands don’t stop smoothing back down your back again, his body draped over yours in full. His teeth brush your spine as he speaks cheerfully.

“SEE? LIKE THIS!”

“Yup!” You squeak out when he finally backs up, feeling your face grow redder and redder even though he’s already back to his own stretches. You want to scold him, for before and now but you are lost in the sensation his body left and frankly you don’t even know what to say because again he seems unfazed. 

Another accident.

* * *

You’re reading too much into this, you know it. But you can’t help your reactions and you can’t help but wonder at the fact that he never has these…’accidents’ when Papyrus is around.

“Whats up, kid?”

“Not a kid, Paps.” But you sigh and continue to stare blankly at the T.V.

“Trouble in paradise?” You can hear the laughter in his voice and you cut a sharp glance toward him.

“There is no paradise—“

“Oh? So just messing around with my baby bro, eh?”

“Wha—No! The hell? I lo—li—” You turn to face him fully, sure you look like an angry lobster by his smug expression until you manage to hiss out, “ _Can you not?_ ”

His grin only widens as he snuggles into the rocking chair, smocking billowing around him as he shrugs, “Just trying to help.”

You narrow your eyes, about to retort when Sans walks in zipping your lips shut without meaning to as you sulk back into the couch. 

“BROTHER! ARE YOU BEING MEAN TO MY HUMAN?”

Your head snaps towards Sans as he sits in his usual place beside you but the slip of the tongue seems to be unnoticed by him even as Papyrus cackles when your skin flushes, Sans looking between the two of you. 

“WHAT IS SO FUNNY?”

“Nothing!” You yelp before Papyrus can stop laughing and say something stupid or anything really. 

“YOU’RE SO RED, HUMAN.” With a groan you cover your face with your hands missing the look of satisfaction crossing the smaller skeletons face as his brother just laughs harder.

* * *

For a few days theres peace and quiet. Or as peaceful and quiet as it can be and the incidents seem to fade from your mind until you see Sans crawling on top the cupboards. 

“Sans!” Your tone is scolding as you scurry forward to make sure the skeleton doesn’t fall but whether it was your shout or his precarious balance he falls back. You barely manage to catch him, his legs winding around your waist before his weight sends you to your knees. “What have we told you about doing that?!”

You wish your words were sharper but their mostly colored by relief tampered with a squeak at the end when you feel a sharp squeeze against your chest. His hands gripping your breasts from when he’d fallen. Hastily you stand, sweeping his hands off with a shudder as he rights himself. 

“SORRY HUMAN, I WAS TRYING TO REACH THE—“

“Here!” You snap, shoving the snacks at him before you flee the kitchen sure even your hands were red as you feel your nipples scrape against your shirt, realizing you hadn’t been wearing a bra. 

Hands. The damn skeleton needed to watch his hands! And you’d tell him…tomorrow.

* * *

Today has been the quietest and you don’t trust it. Especially not when Sans drops his pen for the eight time but this time its accompanied by a small cheer he smothers with an unbelievable ‘oops’. You watch him warily from the corner of your eye as he bends down to pick up his pen, so intent on watching his expression you miss when he uses your thigh for balance until the warmth seeps in. Which isn’t enough to bother you after the last few weeks but when he gets up his hand slides forward, fingers brushing toward the V of your thighs. The rush of warmth it sends through you, much to close to places it shouldn’t be, infuriates you. 

“Damn it, Sans!” You shriek slamming your cup down onto the table. He actually looks a little shocked as he jumps and peers up at you but you can see the guilt flicker on his much too expressive face. But enough is enough. Wrenching his hand from your thigh you yank him towards you, knowing full well he could stop you if he wanted. And when your faces are close enough to feel each others heat you glare at him, voice stern, “That wasn’t nice, Sans, you’ve been doing it on purpose, haven’t you?”

“HUMAN, I—“

“Nope.”

“I AM SORRY, HUMAN.”

“You should be. Are you gonna take your punishment like a man?”

He nods, eyes closing and back tensing as you fight the urge to roll your eyes as you finally let your glare soften. He deserves a little teasing of his own you think as you take a quick breath to gather your courage as you press your lips to his teeth, your own eyes falling shut.

No teasing touches compare to simple act of simply pressing your lips to his, enjoying the way his teeth give slightly under your lips. Its awkward but you can feel his heat more than you have all week. In particular when he clambers up into your lamp, fingers tangling in your hair as you feel the swipe of his magic against your lips, parting them with a groan that he echoes. 

Only when your lips began to feel numb did you finally pull away, face cradled in the small skeletons hands as he grins at you. 

“No more games?” You finally query, a little nervous and his grin widens.

“OH NO, HUMAN. I, THE MAGNIFICENT SANS AM WONDERFUL AT GAMES—“

“Sans!”

“BUT I WILL NOT TEASE YOU ANY FURTHER—“

“Good!”

“NOW I WILL JUST TELL YOU WHEN I WANT YOU—“

“Woah, wait—Sans that is so not—“

“AND THEN I WILL FINALLY LEARN HOW MUCH OF YOUR HUMAN BLOOD VESSELS TURN RED.”

As he finishes his declaration you realize his hands have been moving progressively down until they tug that the collar of your shirt, the angry flush eaten up hungrily by the skeletons gaze. This time you don’t bother to move when Papyrus pops into the kitchen, face actually glowing a faint orange before he smirks.

“Use protection, kids.”

“BROTHER!”

“Go away, Paps!”

**Notes for the Chapter:**

> I've been going back and editing all my work, as well as deleting stories that need re-vamping, and found this little companion piece. Enjoy the not-smut again :P

**Author's Note:**

> Welp. That’s it. I’m in this hole and I’m never coming out apparently. Hope you enjoyed your not smut, Paps is a cockblock :D


End file.
